Suspensions DF2

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swynocker
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49615
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Suspensions DF2
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2010-11-14 22:20:08
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suspensions DF2
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Suspensions DF2
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  1. Suspensions definition
    Contain finely divided solid (suspensoid) distributed giving minimum degree of solubility.
  2. The dispersed phase is _____ where as the contiunous phase is _____.
    Internal, external
  3. Examples of dispersed phase are
    • Colloidal
    • Suspensions
    • Emulsions
    • Microemulsions
  4. T/F There is no such thing as an IV suspension
    True
  5. Advantages of oral suspensions
    Easy to swallow and flexible dosing
  6. Disadvantages of Oral suspensions
    • Microbial growth
    • relative instability (vs solids)
  7. Comminutions is what?
    Particle size reduction
  8. Process of making oral suspension
    Solid drug is comminuted, wetted, then suspended.
  9. Three important issues for suspensions
    • Particle Size
    • Particle wetting
    • Physical stability
  10. Goal for particle size
    1-50 micrometers in diameter
  11. 3 industrial ways to reduce particle size
    • Micropulverization- 1-050 Micro meters
    • Jet milling- <10 micro meters
    • Spray drying
  12. Other methods of particle reduction
    • Electric grinder
    • Spatulations
    • Titrutition
  13. Problems with particle wetting
    Some problems are that the drug might be hydrophobic or there are air pockets
  14. Suspension can be irreversibly altered by these 3 types of physical instability
    Particle settling, aggregation, and growth.
  15. Stokes equation, what do the variables stand for?
    • V- falling velocity
    • d- diameter
    • Ro1- density of sphere
    • ro2- density of liquid
    • g- gravity
    • n- viscosity of dispersion
  16. Stokes parameters
    • Particle size
    • Particle density
    • Dispersion medium viscosity
  17. As particle size decreases what increases?
    Interfacial surface area and free energy
  18. These are types of interparticulate forces
    • Electrostatic- (keeps particles apart)
    • Van der waal- (keeps them together)
    • Repulsive hydration
    • Adhesive
    • Steric Repulsive
  19. Particles aggregate very strongly at _____ and weakly at ________.
    • Primary minimum (close distance)
    • Secondary minimum (far distance)
  20. Coagulation means
    to drive together (strongly bound at primary minimum)
  21. Caking definition
    Combination of settling and coagulation makes a non-redispersable sediment.
  22. Flocculated is usually at the _______ minimum
    Secondary, loose and wooly. Easier to redisperse
  23. Ostwald ripening is the growth of large particles at the expense of ______.
    Small particles
  24. Ostwald ripening is accelerated by
    Temperature fluctuation
  25. Wetting agents help _____ the solids, Flocculating agents help keep them ____, and suspensing agents help keep the solids ______.
    • disperse
    • Apart
    • Suspended
  26. Types of wetting agents are
    Surfactants, solvents, and certain polymers
  27. examples of surfactants
    • Anionic- docusate sodium
    • Ionic- polysorbates (tweens)
  28. Solvent examples are
    Alcohol, glycerol, propylene glycol
  29. Types of flocculating agents
    Electrolytes, Surfactants, and Certain polymers
  30. T/F Dissolution depends on viscosity and bioavailabilty depends on dissolution
    True
  31. For a newtonian liquid shear rate is _______. Viscosity is _______.
    Linear function of shear stress

    constant
  32. According to the graphs, as the line becomes more steeper it becomes _____ viscous.
    Less
  33. For plastic liquids, minimum shear stress must be achieved for what to happen?
    Flow
  34. A thixotropic liquid will __ when aggitated but will form a ___ when standing still.
    Liquefy, Gel
  35. Hysteresis is when the restrictive network ______ reforms.
    Slowly
  36. Xanthan gum is (ionic/anionic) and has ____ temperature stability, and a high _____.
    • Anionic
    • Good
    • High viscosity
  37. Hydroxypropylmethylcellulose is a ______ polymer
    nonionic
  38. Sodium carboxymethylcellulose is an _____ polymer
    Anionic
  39. T/F Gums are not polysaccharides.
    False, they ARE

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